Electric signaling



April 28, 1942. N. HALL ELECTRIC SIGNALING Filed Jan. 21, 1941 2 Sheets-Sheet l INVENTOR NJ. HALL MWWWG A 7' TORNEV April 28, 1942.

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/5 ATTORME'V Patented Apr. 28, 1942 ELECTRIC SIGNALING Nathan 1. Hall, Long Island City, N. Y., assignor to. Bell Telephone Laboratories, Incorporated,

New York, N. Y

., a corporation of New York Application January 21, 1941., Serial No. 5,200

6 Claims.

This invention relates to signalingand particularly to the generation and transmission of electric signals and impulses.

The objects of the invention are to obtain impulses which are accurately fixed in time to enable the duration of the impulse to be controlled with precision; to control ofelectric impulses.

These objects are realized in accordance with the present invention by means of an impulse generator comprising a discharge tube which a second discharge tube which ionizes in responseto the charge accumulated by the condenser at the end of the measured interval to quench the first tube, thereby terminating the impulse. More specifically, the alternating voltage is applied to the control gap of a discharge tube by means of a second tube quenches the first terminate the impulse.

A feature of the invention is an impulse generating system in whichthe phase of the imin the alternating voltage wave at which the discharge tube ionizes. A related feature of the inventi an impulse generating system in which of the impulse Still another feature of the invention is a gen erating system in which the shape of the inn-1 nected to ground.

sistance element pulse is controlled by determining the relative positions 111 the voltage wave These and other features of the invention will be described more fully in the following detailed specification.

In the drawings accompanying the specification:

Fig. 1 discloses an impulsegenerating system designed to produce impulses of positive polari y;

Fig. 2 is a generating system designed to produce impulses of negative polarity;

Fig. 3 is a graph illustrating the phase and shape of the impulses; and

Fig. dis a diagram of a signaling system incorporating the impulse generators.

, The generating system disclosed in Fig. 1 com- 3 and.4 is connected by a conductor 5 to. the anode 6 of a discharge tube 1 and to the anode 8 of a second discharge tube 9. The adjustable of the tube 1. tube 1 is connected througha potentiometer re- The impulse generator has two output circuit terminals. l9 and 20. The terminal I 9 is conmovable contact of the potentiomput terminals; and 20.

Considering the operation of the impulse system shown in Fig. 1, it may be assumed that the curve 22 of Fig. 3 represents the voltage wave produced by the secondary winding of the transformer 2. As the voltage wave 22 enters itspositive half cycle currentflows in a path traceable from the upper terminal of the secondary Wind The cathode I2 oi I3 to ground and also through ing of transformer 2, resistance 3, resistance 4 to ground. The voltage produced by the flow of current through the potentiometer resistance 4 is applied across the control gap ||-l2 of tube 1 in a circuit that may be traced from the movable contact of the potentiometer, resistance 10, electrodes II and I2, resistance l3 and thence to the grounded terminal of potentiometer resistance 4. When the voltage wave 22 reaches the instantaneous value represented by the ordinate 23, the voltage applied across the gap H-l2 is sufficient to ionize the tube. Thereupon current immediately flows in the main discharge circuit of the tube, which may be traced from the upper terminal of the transformer winding, resistance 3, conductor 5, anode 6, cathode l2, resistance 13 to ground. The flow of currentin this circuit sets up a voltage across the resistance i3, and a portion of this voltage, depending upon the setting of the potentiometer contact, is applied to the terminals!!! and 20 to produce a positive impulse in the circuit 2|.

At the same instant the impulse appears across the terminals 19 and 20 the voltage across the resistance 13 causes charging current to flow into the condenser 15. The charging circuit may be traced from the upper terminal of resistance l3 through the variable resistance element l4,,condenser l5 to ground and thence to the grounded lower terminal of resistance element lit. The rate of charge depends upon the Setting of the variable resistance [4, and this setting is seleeted so that the charge on condenser will reach the ionizing voltage of the tube 9 at the instant it is desired tohave the impulse terminate. When the condenser 15 reaches its predetermined voltage, whichmay be chosen to oc= cur at the time the voltage wave 22 reaches the instantaneous value represented by the ordinate 25, the control gap l1-|8 of the tube 9 ionizes. The discharge circuit of the condenser may be traced from the upper pole thereof through the resistance 16, electrodes 11 and 18 to ground. The instant the tube 9 ionizes, its main discharge circuit is closed, and current flows'over con- ;ductor 5, anode 8, cathode l8 directly to ground. The impedance of the discharge circuit of tube 9 'iscomparatively low, and serves as a shunt circuit around the discharge gap of the tube 1.

Therefore, thevoltage across the anode and cathr ode gap of the tube 1 is immediately lowered belowthe sustaining value, and the tube 1 quenches. When the tube 1 quenches, current ceases to flow through the resistance element l3, and the impulse in the circuit 2| is terminated. As the voltage wave 22 declines and approaches the zero value the voltage across the anode-cathode gap of the tube-9 falls below the sustaining value, and the tube 9 quenches.

Thus the impulse commences at a time in the cycle of the wave 22 corresponding to the ordi- 'nate 23 and terminates at a predetermined later time corresponding to the ordinate 25.. The location of these ordinates may be varied by varying the potentiometer 1 and the variable resistance element 14. If it is desired to produce an impulse having a flat top the ordinates 23 and 25 should be selected in the neighborhood of the maximum instantaneous value of the wave since the rate of change is less in this region.

During the negative half cycle of the voltage wave 22 no impulse is produced by the generating system since the discharge tube 1 does not permit current to flow in this direction through the anodecathode circuit.

The generating system shown in Fig. 2 is similar to the one disclosed in Fig. 1, except that it is designed to produce negative instead of positive impulses. When the voltage wave 22 enters its negative half cycle current flows from the lower or grounded terminal of the secondary transformer winding 26 to the grounded terminal of potentiometer resistance 28 thence through said resistance and resistance 21 to the upper terminal of winding 26. As the voltage wave reaches its ordinate value 34 the control gap of the tube 29 is ionized over a circuit traceable from the movable contact of potentiometer 28, resistance 30, control electrode 3|, cathode 32, conductor 33 to the upper terminal of potentiometer resistance 28. As soon as the tube 29 ionizes discharge current flows from the grounded terminal of potentiometer resistance 35 thence through said resistance, anode 36, cathode 32, conductor 33, resistance 21 through the secondary winding 26 to ground. The flow of current through the resistance 35 in this direction produces a negative impulse in the impulse circuit 31. Also the voltage of the anode 36 causes current to flow. through the variable resistance element 38 to charge the condenser 39.

When the condenser 39 reaches a predetermined voltage, which occurs a definite interval following the commencement of the. impulse, namely, when the. voltage wave 22 reaches the ordinate 4|, the tube 40 is ionized. The discharge circuit of condenser 39 may be traced from the upper terminal of said condenser, resistance 42, control gap of electrodes 43 and 44, resistance 45 to ground. The ionization of the gap between the electrodes 43 and 44 causes the main discharge gap of the tube to ionize, and current now flows through the tube from ground, anode 46 to cathode 41, conductor 33, resistance 21 through the winding 26 to ground. The impedance of the discharge circuit of the tube 40 is so low that the tube 29 is quenched, and current ceases to flow through the resistance element 35. Hence the impulse terminates in the circuit 31. As the voltage wave 22 approaches the zero axis the main discharge gap of the tube 40 quenches, and. relay 48 releases.

Hence impulses of negative polarity are generated during the negative alternations of the voltage wave 22, and the phase and duration of these impulses may be controlled by adjusting the potentiometer 28 to determine the starting point of the impulse and by adjusting the variable resistance 38 to determine the terminating point of the impulse.

Fig. 4 illustrates one of the many useful applications of the impulse generating systems shown in Figs. 1 and 2. Assume for example that it is desired to transmit aplurality of different signals over the single transmitting conductor 49. At the transmitting end of the line there are provided a source of alternating current 50 and. a suitable phase generator 5| whereby a plurality of different phases are derived from the source 50. The phase generator 5| has a plurality of output circuits, each of which supplies voltage of a different phase. If ten diilerent phases are required, there will be ten output circuits 52, 53, 54, 55, 56, leading respectively to ten impulse generators 51, 58, 5 9, 69, 6!. These generators are like the one shown in detail in Fig. 1 and produce positive impulses in their output circuits.

At the receiving end of the system a source of alternating current 62 ofthe same frequency as the source 50 and a phase generator 53, similar are provided. Th output cirto generator 5!, v

enerator 53 are connected re- 2, produce negative impulses in their output circuits.

The signals transmitted are registered over the conductor 49 by discharge tube registers iii, "H, 12, I3, 74. To this end the signaling conductor 49 is connected in multiple to the electrodes of all of these register tubes, and the impulse generatorsfi i, 65, t6, etc, are connected individually to the electrodes of the respective tubes.

When it is desired to transmit a signal over the conductor, 49, one or more of the impulse generators 51, 58, etc., at the transmitting end are connected to the line 49 by means of selective switches l5, l6, ii, and positive impulsesof the corresponding phases are sent over the line 19. At the receiving end of the system these incoming impulses are all applied to the electrodes of the ten register tubes ll), ii, 12, etc. For each incoming positive impulse of a particular phase there is applied to some one of the register tubes a negative impulse of the same phase. Therefore, the voltage applied to this particular tube is the sum of the positive and negative voltages and is sufiicient to ionize the tube. None of the remaining tubes, however, has a negative impulse applied simultaneously with the incoming positive impulse, and hence only one of the tubes ionizes in response to each incoming signal impulse. The register tubes serv in any Wellknown manner to utilize the registered signals received over the signaling conductor. For eX- ample, a system illustrating the utility of signals registered on tubes of this characteris in the copending application of W. H. T. Holden, Serial No. 361,537, filed October 17, 1940,

In the generating systems disclosed herein the discharge tubes employed may be of any suitable type such as those having cold cathodes and gasfilled envelopes. However, it will be understood that the invention is not limited to the use of tubes of any particular typ and that tubes having hot cathodes or tubes that are controlled electrostatically may be employed if desired.

The four-element tube shown in Fig. 2 and those illustrated in Fig. 4 scribed in detail in the application of W. H. T. Holden, Serial No. 258,128, filed February 24, 1939.

What is claimed is:

1. The combination in an impulse system of a discharge tube, an impulse conductor, a source of alternating voltage, circuit means for applying said source to said tube to cause the discharge of saidtube when the wave of said voltage source reaches a definite value, a discharge circuit havinga resistance element therein through which current flows following the discharge of said tube, the resultant voltage across said resistance elementserving to produce an impulse in said impulse conductor, a condenser, circuit means for applying to said condenser the voltage of said resistance element to charge said condenser to a given voltagein a predetermined interval following the discharge of said tube, a second discharge tube, circuit means zhereto for causing the discharge of said second ;ube at the end of said predetermined interval, ind a discharge circuit for said second tube for uenching said first tube to terminate said imiulse.

may be of the type deconnecting said condenser disclosed 2. The combinationin animpulsesysten of, a dischargetube having a main discharge gap and a control gap, an impulse circuit, a source alternating voltage, circuitmeans for applying said source to the control gap of said tube to cause the discharge thereof when the wave of said voltage source reaches a predetermined value, a discharge circuit including the main gap of said tube, aresistance element in said discharge circuit through which current fiows in response to the discharge of said main gap following the discharge of said control gap, the resultant voltage across said resistance element serving to produce an impulse in said impulse circuit, a condenser, circuit means for applying to said condenser the voltage across said resistance element to charge said condenser to a, given voltage in a predetermined interval of time, measuring the desired length of said impulse, a second discharge tube, circuit means connecting said condenser thereto for causing the discharge of said second tube at the end of the measured interval, and a main discharge circuit for said second tube for quenching said first tube to terminate said impulse by terminating the flow of current in said resistance element.

3. The combination in an impulse system of a discharge tube, an impulse conductor, a source of alternating voltage, circuit means for applying said source to said tube to cause the discharge of said tube, means for varying in the cycle of the wave of said voltage source the time of the discharge of said tube, a discharge circuit having a resistance element therein through which current flows following the discharge of said tube, the resultant voltage across said resistance elemerit serving to produce an impulse in said impulse conductor, a condenser, circuit means for applying to said condenser the voltage of said resistance element to charge said condenser to a given voltage in a predetermined interval following the discharge of said tube, and means responsive to the voltage on said condenser at the end of said predetermined interval for quenching said tube to terminate said impulse.

4. The combination in an impulse system of a discharge tube, an impulse conductor, a source of alternating voltage, circuit means for applying said source to said tube to cause the discharge of said tube, means for varying thetime in the cycle of the wave of said alternating voltage when said tube discharges, a discharge circuit having an impedance element therein through which cura condenser, circuit means for applying to said condenser the voltage of said impedance element to charge said condenser, means for varying the time required to charge said condenser to a predetermined voltage, a second discharge tube, circult means connecting said condenser to said secor saidtube, the resultant voltages across said resistance element serving to produce a succession of impulses in said impulse circuit, a condenser, circuit means for applying to said condenser the voltages of said resistance element to charge said condenser to a given voltage in a predetermined interval following each discharge of said tube, a second discharge tube, circuit means connecting said condenser thereto for causing the discharge of said second tube at the end of each said predetermined interval, and a discharge circuit for said second tube for quenching said first tube to terminate each of said impulses.

6. The combination in an impulse system of a discharge tube, an impulse circuit, a source of alternating voltage, circu't means for applying said source to said tube to cause successive discharges of said tube in response to the successive cycles of the alternating voltage, a discharge circuit having a resistance element therein through which current flows in response to each discharge of said tube, the resultant voltages across said resistance element serving to produce a succession of impulses in said inpulse circuit, a condenser, circuit means for applying to said condenser the voltages of said resistance element to charge said condenser to a given voltage in a predetermined interval following each discharge of said tube, a second discharge tube, circuit means connecting said condenser thereto for causing the discharge of said second tube at the end of each said predetermined interval, and a discharge circuit for said second tube for shunting the current flowing in the discharge circuit of said first tube to quench said first tube and to terminate said impulses.

NATHAN I. HALL. 

